cup vrs. psi

prkrgrp · Dec 19, 2013

ok I'm trying to load up some new rounds with imr8208 xbr.
the load chart shows cup and psi from what i can tell there is some difference.

do I dare :s0114:

alphapygmy · Dec 19, 2013

I'm not exactly sure what you're asking but here's a link to an interesting page that discusses the correlation between CUP (copper units of pressure) and PSI (pounds per square inch).

http://www.shootingsoftware.com/ftp/psicuparticle2.pdf

AMProducts · Dec 22, 2013

Sweet Jesus! you just asked one of the most complex questions in internal ballistics. The above link does a pretty good job of explaining the differences, and in general I consider the two to be correlated, but unrelated. CUP, LUP (lead units of pressure) and PSI really don't translate in a reasonable fashion to one another. I am inclined to say if you have pressure data for the cartridge in CUP and PSI, and powder data in PSI stick with that. I generally use PSI because I don't have a copper crusher, but I do have a ballistic transducer, which gives me measurement in PSI. Everything else kinda gives me a headache.

prkrgrp · Dec 22, 2013

AMProducts said:
Sweet Jesus! you just asked one of the most complex questions in internal ballistics. The above link does a pretty good job of explaining the differences, and in general I consider the two to be correlated, but unrelated. CUP, LUP (lead units of pressure) and PSI really don't translate in a reasonable fashion to one another. I am inclined to say if you have pressure data for the cartridge in CUP and PSI, and powder data in PSI stick with that. I generally use PSI because I don't have a copper crusher, but I do have a ballistic transducer, which gives me measurement in PSI. Everything else kinda gives me a headache.

hahahaha I try to read as much as I can before posting, the more research I did the more confused I got. and I pretty much came to the same conclusion.
thanks